Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2/00—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions

Definitions

• the present invention relates to a process for the synthesis of olefins from synthesis gas in the presence of at least one Fischer-Tropsch catalyst in a reaction column.
• hydrocarbons from synthesis gas i.e. a mixture of carbon monoxide and hydrogen
• This type of reaction is usually referred to as Fischer-Tropsch synthesis.
• Catalysts which are usually used in this reaction usually comprise metals of group VIIIB of the Periodic Table, in particular Fe, Co, Ni and/or Ru, as catalytically active metals (e.g. v. d. Laan et al. Catal. Rev.-Sci. Eng., 41, 255 (1999)).
• the catalysts used are generally ones which comprise nickel, cobalt, iron or ruthenium, in particular iron, iron and cobalt, iron/cobalt spinel or cobalt/manganese spinel, and also copper-promoted cobalt catalysts.
• GB 1 512 743, GB 1 553 361, GB 1 553 362 and GB 1 553 363 describe catalytic processes for the synthesis of unsaturated hydrocarbons from synthesis gas at from 250 to 350° C. and from 10 to 30 bar.
• the catalysts used here comprise
• U.S. Pat. No. 4,199,523 discloses a Fischer-Tropsch catalyst which comprises at least 60% of iron. Furthermore, this catalyst can comprise promoters such as copper, silver or alkali metals and/or other additives such as zinc oxide, manganese oxide, cerium oxide, vanadium oxide and chromium oxide.
• promoters such as copper, silver or alkali metals and/or other additives such as zinc oxide, manganese oxide, cerium oxide, vanadium oxide and chromium oxide.
• Chang et al describe a process for the conversion of synthesis gas into hydrocarbons enriched with linear ⁇ -olefins, by bringing the synthesis gas at from about 260 to 345° C. into contact with a catalyst comprising a ZSM-5 type zeolite on which metals such as iron, cobalt or ruthenium have been deposited.
• U.S. Pat. No. 5,100,856 describes copper/potassium-promoted iron/zinc catalysts which display improved activity, selectivity and stability in the synthesis of ⁇ -olefins from carbon monoxide and hydrogen.
• composition of the hydrocarbons formed in the Fischer-Tropsch process can be strongly influenced by the choice of the catalysts used, the types of reactor and the reaction conditions.
• WO 02/092216 describes, for example, a Fischer-Tropsch process over a monolithic catalyst support in a reactor which is divided into a plurality of reaction chambers in which the chemical reaction and the physical separation of the products take place.
• the product streams which are discharged from the various chambers differ in terms of their composition. For example, gasoline, kerosene and diesel are discharged separately from the reactor in the present case.
• the object of the present invention is achieved by a process for the synthesis of olefins from synthesis gas in the presence of at least one Fischer-Tropsch catalyst in a reaction column, wherein the synthesis gas is introduced into the reaction column below a zone A of the reaction column and the olefins are taken off below the point at which the synthesis gas is fed in.
• the reaction column used in the process of the invention comprises at least one top zone, a zone A and a bottom zone. Top zone, zone A and bottom zone are arranged in the stated order from the top downward in the reaction column.
• the zone A comprises at least one reaction zone and a distillation zone.
• the synthesis gas is introduced below the zone A but above the bottom zone and the olefins are taken off below the point at which the synthesis gas is fed in.
• the Fischer-Tropsch catalyst is localized in the reaction zone and the Fischer-Tropsch synthesis takes place there.
• the zone of the chemical reaction and the zone of the physical separation are not physically separate.
• a combination zone is present.
• the combination zone is thus a combined reaction and distillation zone.
• the synthesis gas is introduced into the reaction column below the zone A.
• the synthesis gas then comes into contact with the Fischer-Tropsch catalyst and a first hydrocarbon mixture a is formed; unreacted synthesis gas and volatile components of the hydrocarbon mixture formed then ascend into the next reaction zone where a further Fischer-Tropsch reaction takes place and a hydrocarbon mixture b is formed; this process is repeated.
• the volatility of the hydrocarbons formed decreases with increasing chain length and they are then present in liquid form and flow downward into the reaction zone(s) located underneath; there, chain extension by means of synthesis gas present can again take place; this process, too, is repeated. This finally results in a hydrocarbon mixture which can be taken off below zone A.
• This hydrocarbon mixture has, depending on the synthesis gas used, the Fischer-Tropsch catalyst and the process parameters (e.g. geometry of the reaction column, temperature profile of the reaction column, pressure, etc.), a particular molar mass distribution and a particular mean molecular weight. This molar mass distribution is preferably narrower than those of conventional Fischer-Tropsch hydrocarbons.
• the process of the invention thus makes it possible to set firstly the mean molecular weight of the hydrocarbon mixture formed and secondly its molecular weight distribution by means of the superposition of the Fischer-Tropsch process on the distillation process. Furthermore, a higher selectivity to the desired reaction products, i.e. to olefins, in particular ⁇ -olefins, is achieved.
• reaction and distillation zones alternate.
• zone A In a further embodiment of the zone A, combination and distillation zones alternate.
• zone A In a further embodiment of the zone A, a single combination zone is present.
• synthesis gas is introduced at one or more points within the zone A in addition to the introduction of synthesis gas below the zone A.
• water in liquid form is fed in above or within the zone A.
• the Fischer-Tropsch catalyst which is localized in the reaction or combination zone forms a fixed bed, a fluidized bed, a suspension or a bubble column, preferably a fixed bed or a bubble column.
• the Fischer-Tropsch catalyst into the column in the form of packing elements such as Raschig rings, Pall rings, saddle bodies appropriately provided with catalyst.
• packings comprising Fischer-Tropsch catalyst or to use mesh bags filled with Fischer-Tropsch catalyst, known as bales or Texas teabags.
• the packings as such are usually made of sheet metal, expanded metal, wire meshes or knitted meshes which preferably have a cross-channel structure. In these cases, combination zones are generally formed.
• trays for example valve trays, bubble cap trays or related constructions, e.g. tunnel trays or Thormann trays, or sieve trays.
• packings which usually comprise sheet metal, expanded metal, wire meshes or knitted meshes and preferably have a cross-channel structure. Examples are the packings Sulzer MELAPAK, Sulzer BX, Montz B1 types or Montz A3 types.
• disordered packing elements e.g. Raschig rings, Pall rings, saddle bodies, etc.
• a distillation zone usually comprises from 1 to 30 trays, a reaction zone usually comprises one tray and a combination zone usually comprises from 1 to 5 trays. This applies particularly when the reaction and distillation zones or the combination and distillation zones alternate.
• a combination zone comprises from 20 to 100 trays.
• a reaction zone which is provided with packings or with Fischer-Tropsch catalysts in the form of packing elements provided with catalyst or with active distillation packings or with mesh bags filled with Fischer-Tropsch catalyst comprises from 20 to 100 theoretical plates.
• the zone A comprises from one to three distillation zones each having from 10 to 100 trays.
• the zone A comprises a combination zone.
• low boilers can be taken off via the top zone of the reaction column.
• These low boilers generally comprise inert gases such as nitrogen which may be present in the synthesis gas and also any carbon dioxide formed, low-boiling paraffins, in particular methane, low-boiling olefins such as ethene, etc.
• low boilers formed which comprise, for example, any low-boiling paraffins formed, low-boiling olefins and/or water, are taken off from zone A via a side offtake.
• the liquid product taken off via the side offtake can consist of two phases. It is possible for a phase separation to be carried out and the organic phase to be recirculated to the column. In this way, water can be specifically removed from the reaction zone.
• the hydrocarbon mixture formed is removed from the reaction column below the point at which the synthesis gas is fed in. This can be achieved via a side offtake. However, it is also possible to take off the hydrocarbon mixture formed via the bottom of the column.
• part of the hydrocarbon mixture formed is taken off from zone A via a side offtake and the other part of the hydrocarbon mixture formed is taken off below the point at which the synthesis gas is fed in.
• reaction column used comprises a top zone, a zone A and a bottom zone.
• the reaction column used comprises a top zone, a zone A and a bottom zone and also a distillation zone B which is localized between the zone A and the bottom zone.
• Internals having a distillative separation action can be installed or packings can be comprised in this distillation zone.
• the embodiments of the internals or packings are analogous to those of the distillation zones of the zone A.
• the reaction column used comprises a top zone, a zone A and a bottom zone and also a distillation zone C which is localized between the top zone and the zone A.
• Internals having a distillative separation action can be installed or packings can be comprised in this distillation zone.
• the embodiments of the internals or packings are analogous to those of the distillation zones of the zone A.
• the reaction column used comprises a top zone, a zone A and a bottom zone and also a distillation zone B which is localized between the zone A and the bottom zone and a distillation zone C which is localized between the top zone and the zone A.
• Internals having a distillative separation action or packings can be comprised in these distillation zones B and C.
• the embodiments of the internals or packings are analogous to those of the distillation zones of the zone A.
• the synthesis gas used in the process of the invention can be produced by generally known processes (as described, for example, in Weissermel et al., Industrial Organic Chemistry, Wiley-VCH, Weinheim, 2003, 15-24), for example reaction of coal or methane with steam or by comproportionation of methane with carbon dioxide. It usually has a ratio of carbon monoxide to hydrogen of from 3:1 to 1:3. Preference is given to using a synthesis gas which has a mixing ratio of carbon monoxide to hydrogen of from 1:0.5 to 1:2.5.
• Fischer-Tropsch catalysts which preferentially catalyze the formation of olefins, in particular ⁇ -olefins.
• Possible catalysts here are, in particular, Fischer-Tropsch catalysts comprising iron, iron and cobalt, iron/cobalt spinel or cobalt/manganese spinel and also copper-promoted cobalt Fischer-Tropsch catalysts.
• the catalysts described in GB 1 512 743, GB 1 553 361, GB 1 553 362, GB 1 553 363, U.S. Pat. No. 4,199,523, U.S. Pat. No. 4,418,155, U.S. Pat. No. 5,100,856 are incorporated by reference into the present invention.
• the process of the invention is usually carried out at from 150 to 350° C.
• the pressure here is from 1 to 60 bar, preferably from 10 to 50 bar.
• the GHSV gas hourly space velocity
• the GHSV is generally from 100 to 30 000 parts by volume of feed stream per part by volume of catalyst and hour (l/l ⁇ h).
• the product obtained in the process of the invention which is removed from the reaction column below the point at which the synthesis gas is fed in, is a mixture of a plurality of hydrocarbons.
• This mixture has a particular mean molar mass and a particular molecular weight distribution.
• This product preferably comprises at least 50% by weight of olefins, preferably ⁇ -olefins.
• the olefins obtained generally have from 4 to 20 carbon atoms, preferably from 5 to 14.
• a product comprising at least 50% by weight of olefins having from 5 to 7 carbon atoms, of which in turn at least 50% by weight is made up of one or more ⁇ -olefins, in particular 1-pentene and 1-hexene, is obtained.
• a product comprising at least 50% by weight of olefins having from 8 to 14 carbon atoms, of which in turn at least 50% by weight is made up of one or more ⁇ -olefins, is obtained.
• a product comprising at least 50% by weight of olefins having from 15 to 20 carbon atoms, of which in turn at least 50% by weight is made up of one or more ⁇ -olefins, is obtained.
• ⁇ -olefin or a mixture of ⁇ -olefins whose number of carbon atoms is at least 1 less than that of the olefin mainly formed which can be separated off below the zone A into the zone A of the reaction column during start-up of the process.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (3)

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Cited By (5)

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• 2005
  • 2005-11-28 DE DE102005056784A patent/DE102005056784A1/de not_active Withdrawn
• 2006
  • 2006-11-23 RU RU2008126153/04A patent/RU2008126153A/ru not_active Application Discontinuation
  • 2006-11-23 CN CNA2006800445704A patent/CN101316914A/zh active Pending
  • 2006-11-23 US US12/095,127 patent/US20090005464A1/en not_active Abandoned
  • 2006-11-23 BR BRPI0619015A patent/BRPI0619015A2/pt not_active IP Right Cessation
  • 2006-11-23 EP EP06819684A patent/EP1957614A1/de not_active Withdrawn
  • 2006-11-23 CA CA002630380A patent/CA2630380A1/en not_active Abandoned
  • 2006-11-23 WO PCT/EP2006/068780 patent/WO2007060186A1/de not_active Ceased
  • 2006-11-28 AR ARP060105238A patent/AR057191A1/es unknown
• 2008
  • 2008-05-07 NO NO20082131A patent/NO20082131L/no not_active Application Discontinuation

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